1. Field of the Invention
The invention refers to a sound permeable loud-speaker cover having a frame in which are arranged mutually crossing rods of a synthetic plastic material and delimiting sound passage openings and further having a sound-permeable material covering the sound passage openings.
2. Description of the Prior Art
It is known to cover the cone of loud-speakers by a loud-speaker cover having the shape of a lattice, allowing the passage of sound but preventing the loudspeaker cone from becoming mechanically damaged. It is also known to produce the webs delimiting the sound passage openings from synthetic plastic material according to an injection molding process.
If loudspeaker are arranged in a position in which the loudspeaker cover extends essentially along a horizontal plane, as is for example the case when mounting loudspeakers in the tail turret of motor vehicles, there exists the risk that dirt particles, foreign bodies or the like fall through the sound passage openings of the loudspeaker cover into the conically shaped diaphragm of the loudspeaker and thus give rise to at least a distortion of the sound reproduced by the loudspeaker. Pointed objects falling through the lattice openings may even cause damage to the speaker cone.
For the purpose of avoiding this drawback, it has already been proposed to additionally cover the sound passage openings by a sheet of a sound-permeable material, which sheet is, for example, fixed to the loudspeaker cover by glueing to that side of the loudspeaker cover which faces the speaker cone. In this known arrangement, there exists the risk that the sound-permeable material becomes, particularly when having been applied in an improper manner, at least partially loosened from the webs, so that the particles retained by this sound-permeable material fall into the speaker cone.
In order to overcome this drawback, there has already been proposed a loudspeaker cover consisting of two independently produced lattices formed of webs and having clamped therebetween a plurality of layers consisting of a mesh of synthetic plastic material, noting that both lattices are held together by means of a screw. It is a drawback of this known construction that both lattices must separately be produced and that there exists the risk that the screw becomes, in particular on account of the vibrations generated during operation of the loudspeaker, loosened or even completely unscrewed, so that in case of an approximately horizontal arrangement of the loudspeaker cover particles may again fall into the speaker cone or strays, resonance phenomena or the like may at least occur on account of the loose connection of both lattices.
A loudspeaker cover consisting only of sheets of fabric being clamped between two frames connected one with the other is also known. In this known loudspeaker cover having no webs crossing one or the other, there exists the risk that the fabric sheets may become damaged, for example perforated, particularly in those cases in which the loudspeakers are arranged in the tail turret of motor vehicles and heavy or sharp-edged objects are put into this tail turret.
It is an object of the present invention to provide a loudspeaker cover which can be produced in a simple manner and which reliably prevents foreign bodies from penetrating into the speaker cone even in case of a substantially horizontal arrangement of the cover.
It is a further object of the present invention to provide a loudspeaker cover in which an inseparable connection is warranted between the webs delimiting the sound passage openings and the sound-permeable synthetic plastic material.
Furthermore, it is an object of the present invention to provide a process allowing manufacture of a loudspeaker cover in a simple and money-saving manner.